In many different applications, electrical input devices have replaced mechanical input devices because the electrical input devices have fewer moving components. With fewer moving components, electrical input devices are less likely to fail due to wear and thus are more reliable. However, electrical input devices lack the tactile feedback provided by the interaction of moving parts within mechanical input devices. Thus, electrical input devices rely on visual, auditory, kinesthetic, and/or tactile cues to provide feedback to the user. Kinesthetic feedback (such as active and resistive force feedback) and tactile feedback (such as vibration, texture, and heat) are collectively referred to as “haptic feedback.” Haptic feedback can be used to convey physical force sensations to the user, and generally, the physical forces simulate actuating a traditional mechanical button or switch and provide the user with an indication that the user's input has been accepted.
In automotive applications, electrical input devices are often used in place of mechanical input devices in systems, such as audio systems, heating and cooling systems, navigation systems, lighting systems, and other systems. In many cases, the electrical input device replaces a mechanical rotary switch. Thus, the electrical rotary switch must feel and respond like the traditional mechanical rotary switch that it replaces. The mechanical feel and response is simulated by haptic feedback.
Haptic feedback in electrical rotary switches can be provided in several different ways. First, the torque versus displacement of the rotary switch, also known as the detent amplitude, can be varied so that the torque required to turn the electrical rotary switch can become smaller or larger as the switch is rotated. Second, the allowable displacement of the electrical rotary switch can be varied so that the rotary switch allows only partial rotation (rotates less than 360°) or allows continuous rotation (rotates more than 360°). Third, the number of detents per possible rotation of the electrical rotary switch can be varied. And lastly, the background friction torque of the electrical rotary switch can be varied to make the rotary switch easier or harder to rotate.
Haptic feedback in a rotary switch is provided through a knob that is assembled to an encoder. The encoder can have separate detent and spring members or a combined detent and spring member. Generally, haptic feedback is provided by a detent profile, or a cam surface, that acts upon the detent, or a cam follower, which changes the compression of the spring member. Also, it is desirable to have variable tactile effects, i.e., a different feel for different functions. Such variable tactile effects are provided by programmable rotary controls that have an electromechanical device, such as a DC motor or electro-magnetic clutch break. Programmable rotary controls with an electromechanical device provide a near infinite variety of tactile effects. However, in most applications, a near infinite variety of tactile effects is unnecessary, and only a few different kinds of tactile effects are required. Thus, a user that needs, for example, only two or three different tactile effects has to acquire a more costly rotary switch with a near infinite number of tactile effects.
Thus, there is a need for a rotary switch assembly with adjustable and variable haptic effects. Also, there is a need for a rotary switch assembly with fewer options for haptic effects, thus reducing manufacturing costs of the rotary switch assembly.